Radiator Size Calculator

Calculates radiator sizes in kW and BTU

Radiator Sizing Calculator - What Size Radiator Do I Need

This radiator size calculator will help calculate the correct radiator size heat output (in BTU and KW) when designing a new central heating system or adding rooms to an existing system

This radiator calculator tool will help you in getting the correct heat output for your radiators

Enter Room Sizes For Radiator Sizing

Room Height (m)
Room Width (m)
Room Length (m)
Use Of Room
North Facing?
Room has French Doors?

What is the Perfect Temperature for a Room

A common preferred temperature is below but obviously this varies depending on personal preference

  • Lounge - 21 C (70 F)
  • Bedroom - 18 C (64.4 F)

Limitations of Online Radiator Sizing Calculators

Most of the online radiator calculators, including this one, use various factors to estimate the required radiator size heat output (KW and BTU). They provide a good estimate of required BTU output and a useful check on figures your heating engineer may be specifying in a quote.

They are limited by the factors they take into account